Vibratory feeders are typically used to improve productivity in automated manufacturing processes. The feeders deliver articles such as component parts for subsequent use, e.g., by a base assembly machine in the manufacture of a subassembly or a final product.
Such vibratory feeders may be used for feeding flanged articles. These articles include headed fasteners, e.g., screws, nails, pop rivets and other flanged parts such as syringes, fittings and the like. A typical vibratory bowl feeding system comprises a feeder bowl mounted for controlled vibratory motion on a vibratory driver. Specially tooled, internal tracks are formed within the bowl in a helical configuration between a bottom of the bowl and a discharge at a top of the bowl. The vibratory driver may be of a fixed angle or variable angle type suitable for vibrating the feeder bowl to feed the articles along the tracks to the feeder bowl discharge outlet. Additionally, specially tooled surfaces may be mounted between the discharge outlet of the feeder bowl and a final location designated for delivery of the articles being fed, e.g., to a downstream assembly machine.
It is normally desirable that the aforementioned flanged articles be discharged in a particular vertical orientation. A traditional prior art method for vertically orienting a flanged article is to form a longitudinally extending gap or slot in the feeder bowl tooling surface and to rely on the bodies of the articles to fall through the slot into a vertical or upright position. The flange of the article is thereafter supported for movement on flat "running surfaces" or planar transfer surfaces formed on both sides of the slot, and the vibratory bowl motion imparts movement to the articles for discharging them from the feeder bowl. That slot allows the body of a part to fall through randomly and is normally fabricated in the bowl with a gap width dedicated to the corresponding part diameter or body size.
The surface-to-surface or surface bearing contact areas between the flanged surfaces of the articles and the planar transfer surfaces is a function of the gap width which is slightly larger than the body size to allow free movement. In a typical application, wherein a part having a 1 inch flange diameter, a 1/4 inch body diameter and feed rails having a discharge slot with a 0.260 inch gap width to accommodate manufacturing tolerances and free movement are provided, about two-thirds of the bottom surface area of the flange is in surface contact with the track. Because of the resulting frictional resistance between these surfaces, the delivery rate of the feeder is reduced. Accordingly, the feed rate is conventionally increased by increasing the vibrational amplitude and/or frequency of the driver; however, excessive "bouncing" of articles may result, thereby reducing the number of articles delivered to the slot from the internal track and also commonly causing jamming of adjacent articles due to the articles rocking back and forth within the discharge slot resulting in overlapping of their flanges on the planar transfer surfaces. Additionally, the width of the slot may be increased somewhat in these conventional structures to reduce the bearing surface contact; however, the articles then may become unstable on the feed rails, thereby reducing the feed rate and again causing jams typically due to overlapping of the flanges of the articles.